Bee cluster, flying and active temps

Honeybee winter cluster

It always seems an item for discussion when we talk about our bees and the temperature. You can read a dozen different articles and still have questions. Here's my take on the subject.  Many a beekeeper has watched his bees during winter and cold snaps. A close watch of the temperature and the beekeeper knows when they are flying or not. A better understanding of the thermal reaction of bees might be of interest.

The temps given in this article is a general guideline. There are three temperatures that are important to the bees:

1. The temperature of their body. When the bees' body temp hits about 57 they will start to cluster for warmth in the hive.  If the body temperature of the bee falls below 50, paralysis of the muscles start to occur, at 45 their "frozen" meaning their muscles can no longer move.  You may have seen this but didn't understand why the bee seems "frozen". Many times they will leave the hive or land nearby, become chilled as their body temperature falls as they fail to return to the hive.
2. The temperature of the air. Air temperature has a great affect on the bees. Activity as seen in flying is usually performed in the range of 50 to 110. If the air ambient temperature is about 64 or high, the bees inside the hive do not cluster. At about 48 the bees will have a defined cluster. Cleansing flights will still occur down to about 44 as their body temp is still slightly higher and they can do this for short flights.
3. The temperature of the bee cluster. The middle of the cluster is about 95, The outer edges of the cluster is less. Bees from the outside edge of the cluster change places and make their way deeper into the cluster to warm up.  Warm bees replace them on the outside edge.

Now some would include the bee brood temperature  in the above, but that is not the focus of this post. So why is all of this important? If you understand how these temperatures affect the bee, you can better identify what is going on with them and make sound management plans and actions.

There is still one more area to understand and that is the thermal properties of your hive.

Each hive design has strengths and weaknesses. In addition, the beekeeper makes decisions about additions and deletions from the base design. Some examples of this might be the addition of a vented cover, a insulated top, a reduced entrance or a dark wrap around the hive. Additionally, the beekeeper might make management decisions external to the hive such as adding a wind break or painting the hive a different color.

These factors can be used to change the dynamics of the apiary.